In association with the recent tendency for a higher degree of integration in a semiconductor device having multilayered metal wirings designed under a rule of 0.25 micron or below, as a clearance between the metal wiring layers has become increasingly smaller, impedance between the metal wirings increases due to electrostatic induction, which may lead to some disadvantageous results such as a delay in a response speed or increase of power consumption. To overcome this problem, it is required to make as much as lower a dielectric constant of an interlayer insulating film which is provided between the metal wirings made of aluminum or copper, on a semiconductor substrate.
The interlayer insulating film provided for the purpose as described above is generally formed on a semiconductor substrate by using the vapor-phase growth method such as the CVD (Chemical Vapor Deposition) method, or the coating method such as the spin coating method.
By using the latest technique based on the CVD method (as described, for instance, in Patent 1), it is possible to obtain a silica-based coating film with the dielectric constant of 3 or below, but it is generally considered that it is difficult to form a CVD insulating film with the dielectric constant of 2.5 or below, and also like in the coating method based on the conventional technology, there is the problem that, as a dielectric constant of the film becomes lower, strength of the film becomes lower. Furthermore, in the CVD insulating films made of a polyallyl resin, a fluorine-added polyimide resin, or a fluorine resin, or in a coating film formed with a coating liquid of any of such resin materials, the dielectric constant may be around 2, but the adhesiveness to a surface of a semiconductor substrate and also to a resist material used in micro-fabrication are low, and furthermore there is also the problem that the chemical resistance and the resistance against oxygen plasma are disadvantageously low.
In the coating films obtained by using a coating liquid for forming a silica-based coating film containing partial hydrolysate or hydrolysate of alkoxysilane and/or halogenated silane, although it is possible to obtain a coating film with the dielectric constant of 3 or below, it is difficult to achieve the dielectric constant of 2.5 or below, and there is also the problem, for instance, that the adhesiveness to a coated surface is low.
The present inventors made intensive researches for solving the problems as described above, and it is possible to form a coating film with the dielectric constant of 3 or below, which is excellent in adhesiveness to a coated surface, film strength, chemical resistance such as resistance against alkali, cracking resistance, and surface flatness and also which is excellent in resistance against oxygen plasma and workability of etching, by using a) a coating liquid for forming a low dielectric constant silica-based coating film, containing polysiloxane which is a product between alkoxysilane and/or halogenated silane or hydrolysate of any of the materials and fine silica particles (as described, for instance, in Patent document 2); b) a coating liquid for forming a low dielectric constant silica-based coating film, containing alkoxysilane and/or halogenated silane or hydrolysate of any of the materials and an easily decomposable resin which is decomposed or vaporized at 500° C. or below (as described, for instance, in Patent document 3), c) a coating liquid for forming a low dielectric constant silica-based coating film, containing polysiloxane which is a product between alkoxysilane and/or halogenated silane or hydrolysate of any of the materials and fine silica particles and an easily decomposable resin which is decomposed or vaporized at 500° C. or below (as described, for instance, in Patent document 4), or d) a coating liquid for forming a low dielectric constant silica-based coating film, containing alkoxysilane and/or halogenated silane or hydrolysate of any of the materials and an organic template material (as described, for instance, in Patent document 5).
However, the present inventors repeated a lot of examinations for forming a low dielectric constant silica-based coating film on various types of semiconductor substrates by using the coating liquids as described above and known methods for forming a coating film (such as the spin coating method or other coating method) and found that, although a coating film having the characteristics as described above could be obtained, strength of the coating film became lower when it was tried to form a coating film having a dielectric constant of 2.5 or below, and also that it was difficult to stably obtain a coating film having the Young's modulus of at least 3.0 GPa (Giga Pascal) or more as required by the semiconductor device manufacturers.
On the other hand, researchers in Tohoku University reported that it is possible to use an organic/inorganic hybrid zeolite having an organic group in the framework, which can provide a material for forming a coating film having a low dielectric constant, and that the material can be synthesized with bis(triethoxysilyl)methane (as described, for instance, in Non-patent document 1).
In relation to this report, there have been proposed a zeolite having an aliphatic group selected from the group consisting of alkylene, alkenylene, and alkadienylene in the framework as obtained by subjecting water and the organic silicon compound expressed by general formula (1) at a temperature from 80 to 260° C. and preferably from 90 to 220° C. to a hydrothermal reaction, and a method for synthesizing the zeolite (as described, for instance, in Patent document 6):

Although the coating film obtained from the above material has a high Young's modulus, there is a defect that the surface is substantially rough, because the particle size of the zeolite substances contained in the coating film is relatively large and around 20 nm. When an interlayer insulating film or the like is formed with the material, complicated operations such as a chemical and mechanical polishing are required to make a surface of the coating film smooth.
As a composition for forming a coating film having a low dielectric constant and a high adhesiveness, there have been proposed, for instance, a composition for forming a coating film containing a hydrolyzed condensate obtained by hydrolytic condensation of, for instance, the silane compound A expressed by general formula (2) and the silane compound B expressed by general formula (3) (wherein Ry denotes a bivalent organic group having a double bond of carbon or a triple bond of carbon, and a laminated film formed with the composition:

However, because Ry constituting the silane compound B is a bivalent organic group having a double bond or a triple bond of carbon, when the composition for forming a coating film is thermally cured, the composition reacts to a polymer (for instance, an organic polymer) in other films contacting the silica-based film, and adhesiveness with the other film is improved, but the use for such purpose as described above is rather a rare case. When the composition is used for other purposes, there may occur some troubles such as deterioration in resistance against plasma or heat resistance of the coating film.
The inventors made keen efforts for solving the problems as described above, and found that the problems can be solved by forming a coating film on a substrate by using a coating liquid for forming a coating film, having a novel composition and novel characteristics as described below, and completed the present invention.    Patent document 1: JP2000-349083A    Patent document 2: JPH09-315812A    Patent document 3: WO00-18847A    Patent document 4: WO00-12640A    Patent document 5: JP2002-30249A    Patent document 6: JP2002-211917A    Patent document 7: JP2005-133040A    Non patent document 1: “Novel organic-inorganic hybrid zeolite having an organic group in the framework”, Chemistry and Industries, Vol. 57, No. 5, p. 512 to p. 514 (2004)